[15a-A35-1~10] 9.4 Thermoelectric conversion

[15a-A35-2] Electronic structures and thermoelectric transport properties of delafossite-type complex nitrides CuMN₂ (M=Ta, Nb)

〇Isao Ohkubo^1,2, Takao Mori¹ (1.NIMS, 2.JST-PRESTO)

Keywords:Layered complex nitride, Electronic structure calculation

Layered compounds have several advantages with respect to high-performance thermoelectric properties. In this study, we focused on the delafossite-type layered complex nitrides CuMN₂ (M = Ta, Nb). Density-functional theory and Boltzmann theory calculations were performed to determine the electronic structures and thermoelectric transport coefficients of the CuMN₂ compounds. CuMN₂ materials were semiconductors with energy band gaps of 1.09 eV for CuNbN₂, 1.66 eV for CuTaN₂, and have the potential to be p-type semiconductors because tops of valence bands are mainly contributed by Cu 3d and N 2p orbitals as well as p-type semiconducting delafossite-type oxide CuAlO₂. Calculation results exhibited less anisotropic and unusual thermoelectric transport properties due to their valence band structures.